In LTE, “eICIC (Enhanced Inter-Cell Interference Coordination)” has been studied in which in ABS (Almost Blank Subframe), a radio base station eNB reduces transmission power on a PDSCH (Physical Downlink Shared Channel) for a mobile station UE in an “RRC Connected state” in a macrocell to a level not interfering with a mobile station UE in an “RRC Connected state” in a picocell, as shown in FIG. 11(a).
However, when 16 QAM or 64 QAM is applied, the mobile station UE estimates the amplitude of a received signal based on an offset value between transmission power of a signaled CRS (Cell-specific Reference Signal) and the transmission power on the PDSCH. This leads to a problem that an appropriate demodulation process on a received signal cannot be performed when the transmission power on the PDSCH is reduced only in ABS.
In order to solve the above problem, it has been proposed that the radio base station eNB signals the offset value in ABS via an upper layer to the mobile station UE as shown in FIG. 11(b) (see, e.g., Non-patent documents 1 and 2).